"We will not be the first to violate the accord, but they [the U.S.] should know that they will regret it if they withdraw from it", Rouhani asserted. His speech was broadcast live on Iranianstate TV.

Rouhani was speaking as Tehran marked National Nuclear Technology Day.

It remains unclear who carried out the attack.

"I would like to tell the Iranian nation that our nuclear industry is now moving forward more strongly and accurately than before", he noted, adding that the clear message of the nuclear achievements unveiled on Monday is the faster spinning of Iran's centrifuges.

In early March, Iranian Foreign Minister Mohammad Javad Zarif forewarned on state television: "If the United States makes the mistake of pulling out of the JCPOA, it will definitely be a painful mistake for the Americans".

The Syrian Observatory for Human Rights, which is based in the United Kingdom, said that 14 people, mostly from Iran's military or its proxy forces, were killed in the airstrikes.

Some officials have said the rial's slide is part of a wider political conspiracy against moderate President Hassan Rouhani by his opponents that seeks to discredit his government and reignite the unrest that rattled the country in December.

Iranians stand in front of a bank, hoping to buy US dollars at the new official exchange rate announced by the government, in downtown Tehran, Iran, Tuesday, April 10, 2018.

IRNA, Iran's official news agency, said the attack apparently affected 200,000 router switches across the world, including 3,500 in Iran, Reutersreported.

He said "preparations have already been made" without giving more details.

The U.S. dollar jumped in a day from 54,700 rials to 58,000 rials in the open market in Tehran, local media reported. He also apparently said that just two per cent of devices in Iran were affected.

A decision to withhold a waiver would have effectively ended the deal between Iran, the U.S., China, France, Russia, Britain, Germany and the European Union.

The missile attack followed a suspected poison gas attack on Saturday on the last remaining foothold for the Syrian opposition in the eastern suburbs of Damascus.